1. Technical Field
The present invention relates to networked communications such as ad-hoc networks, and, more particularly to mobile ad-hoc networks (MANET).
2. Description of the Related Art
There are three different ways to conduct a MANET experiment: (1) actual field exercises, (2) simulation, and (3) emulation. An actual field exercise is the most expensive one in terms of time, effort, resources, and human power. Simulation provides a controllable, repeatable virtual environment in which theoretical concepts are implemented and evaluated. Emulation is between the two; it also provides a controllable and repeatable environment in which one can conduct and repeat experimentation in a physical test bed—not in a virtual environment as simulation does.
The invention is intended mainly to support emulation although its outputs can also be used to feed a simulation tool; e.g., the time-stamped positions or also known as mobility traces or traces or a mobility scenario or simply just scenario. Both simulation and emulation requires a scenario, which is a mobility scenario for the mobile ad-hoc network emulator (MANE) test bed or a set of topology definitions for an emulation test bed that uses a packet-filtering tool to create virtual topologies in a physical network such as the TEALab test bed. The invention is intended mainly to support the MANE and the TEALab test beds. The functionality of the two test beds are described in subsequent sections.
The present invention relates to providing high quality information assurance in a networking environment. Military tactical communications require network security precautions that are distinct from the commercial world. However, the underlying characteristic is the fluid nature of the environment, since network participants are mobile. Group make-up varies over time, since units join and leave on an ad hoc basis. Thus, communication links vary both quality and reach. Unit responsibilities also shift as mission requirements and battlefield circumstances dictate. There may be no fixed infrastructure that can be relied upon. In addition, equipment may be captured by adversaries who are highly motivated, extremely skilled, and well funded. Security in such an environment is vital to the network warfare operation.
The present invention relates to the emulation and simulation of wireless, mobile networks. As used herein, a network topology is a pattern of links connecting pairs of nodes of a network. A node is a device that is connected as part of a computer network, and a data link is the means of connecting. It can be appreciated that in the course of movement of wireless operators, the ability of the operators to communicate with one another is of paramount importance. Rather than carry out the network capability measurements during actual real world experimental work to determine the communication links created or destroyed as the operators move in predetermined areas, simulation programs and emulation test beds are used to predict the networking capabilities.
A more complete description of the characteristics of Mobile Ad Hoc Networks is found in RFC# 2501 (http://www.ietf.org/rfc/rfc2501.txt) entitled “Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations,” by S. Corson of University of Maryland and J. Macker of Naval Research Laboratory, January 1999. As stated therein, a MANET consists of mobile platforms (e.g., a router with multiple hosts and wireless communications devices)—herein simply referred to as “nodes”—which are free to move about arbitrarily. The nodes may be located in or on airplanes, ships, trucks, cars, perhaps even on people or very small devices, and there may be multiple hosts per router. A MANET is an autonomous system of mobile nodes. The system may operate in isolation, or may have gateways to and interface with a fixed network. In the latter operational mode, it is typically envisioned to operate as a “stub” network connecting to a fixed internetwork. Stub networks carry traffic originating at and/or destined for internal nodes, but do not permit exogenous traffic to “transit” through the stub network. MANET nodes are equipped with wireless transmitters and receivers using antennas which may be omnidirectional (broadcast), highly-directional (point-to-point), possibly steerable, or some combination thereof. At a given point in time, depending on the nodes' positions and their transmitter and receiver coverage patterns, transmission power levels and co-channel interference levels, a wireless connectivity in the form of a random, multihop graph or “ad hoc” network exists between the nodes. This ad hoc topology may change with time as the nodes move or adjust their transmission and reception parameters.
The characteristics of MANETs include (1) Dynamic topologies due to arbitrary movement of nodes which arbitrarily changes network topology, which may consist of both bidirectional and unidirectional links, (2) Bandwidth-constrained, variable capacity links and the realized throughput of wireless communications when taking into consideration the effects of multiple access, fading, noise, interference conditions, etc. is often much less than a radio's maximum transmission rate; (3) Energy-constrained operation due to reliance at least in part on batteries or the like, requiring optimal energy conservation; (4) Limited physical security due to the increased possibility of eavesdropping, spoofing, and denial-of-service attack such that decentralized nature of network control in MANETs provides additional robustness against the single points of failure of more centralized approaches. In addition, MANETS may be tens or hundreds of nodes per routing area.
Simulation is a leading way to research solutions to difficult Mobile Ad Hoc Networks (MANETs), which are wireless mobile nodes that cooperatively form a network without reliance on an existing infrastructure. There is no coordination or configuration prior to setup of a MANET. Routing packets are used in an environment where the topology is changing frequently creating wireless communications issues, and resource issues such as limited power and storage.
There are several factors involved in conducting trustworthy simulation-based research. Generally, there are four areas of credibility in research. 1. Repeatable: A fellow researcher should be able to repeat the results for his/her own satisfaction, future reviews, or further development. 2. Unbiased: The results must not be specific to the scenario used in the experiment. 3. Rigorous: The scenarios and conditions used to test the experiment must truly exercise the aspect of MANETs being studied. 4. Statistically sound: The execution and analysis of the experiment must be based on mathematical principles.
Executing the simulation can require a lot of time and effort. Therefore, it is important to conduct the execution portion correctly and expediently. In a publication entitled “MANET Simulation Studies: The Incredibles,” several common simulation pitfalls were enumerated. Simulation setup involves determining (a) type: terminating or steady-state), (b) model validation & verification, (c) PRNG Validation & Verification (PNRG is a package for maintaining and visualizing network data, particularly historical trend analysis of network resources), (d) variable definitions (hundreds of configurable variables may be used during an execution in order to meet general wired and wireless network simulator requirements), and (e) scenario development (using the correct parameters, including the number of nodes, the size of the simulation area, and the transmission range of nodes used in the simulations). Simulation execution involves: (a) setting the PRNG seed, (b) scenario initialization, and (c) metric collection. Output analysis requires (a) analysis of proper size of data sets, (b) statistical analysis and (c) confidence intervals.
The present invention is directed to a methodology of custom-designing network topology and creating time-stamped position data to drive, inter alia, the Mobile Ad-hoc Network Emulator (MANE) system consisting of hardware and software. Downloadable examples of the MANE software are presented at http://downloads.pf.itd.nrl.navy.mil/mane/, which are hereby incorporated by reference as though fully rewritten herein. The MANE emulator is a mobile ad hoc network emulator that provides the ability to emulate dynamic link connectivity between emulated mobile nodes in a laboratory test bed. MANE runs on a network of servers, each of which hosts a number of client test nodes (TNs) as shown in FIG. 1(A). The servers LAN approach support emulation scalability. It is based upon motion interface upon global positioning system (GPS) reference location data so that the same test tools, methods, and tracing tools can be used in the real world test with actual working GPS components.
MANE runs on a network of servers, each of which hosts a number of client test nodes (TNs). The servers LAN approach support emulation scalability (see FIG. 1A). Although MANE runs on a Linux operating system, the overall design accommodates heterogeneous operating systems among the TNs. Furthermore, MANE is protocol independent, and can support multiple protocols (e.g., IPv4, IPv6, ARP, etc.). The MANE connectivity model provides packet dropping based on the range between individual nodes, the transmission power, and packet size.
MANE components consists of:
(1) Forwarding Engine: This component runs on the MANE servers. It sniffs packets on the servers interfaces, and forwards them to the all other servers interfaces. The forwarding engine interconnects all the emulated mobile nodes (TNs).
(2) Range Model: This component runs on the MANE servers. It generates the connectivity matrix that determines which packets get dropped. The range model works in conjunction with the forwarding engine and creates a dynamic connectivity model on the servers.
(3) GPS Emulator: This component reads position information from scripts for each emulated mobile node and multicasts the positions out to the MANE forwarding engine/range model and to the individual emulated nodes. There is one GPS emulator in MANE, and it resides either on the test bed control node, or on one of the MANE servers.
(4) GPS Daemon: This component resides on each of the emulated mobile nodes. It listens to the GPS emulator multicasts and keeps track of the node position. It can supply GPS position information to applications that require it.
(5) TN Packet Treatment: This component resides on each of the emulated mobile nodes. It emulates the effects of a simple Media Access Control (MAC) scheme by limiting the total amount of inbound and outbound traffic at a test node. This module creates a virtual interface over which all MANET communications must take place. Each of the components obtains testbed configuration information from a common configuration file, which by default is located in /etc/mane.config.
The present invention is also directed to a methodology of creating an ordered list of textual topology definitions to drive, inter alia, the TEALab test bed. For a more thorough description of this test bed, see “TEALab: A Testbed for Ad hoc Networking Security Research,” by Mike Little, Telcordia Technologies Inc., Piscataway, N.J. 08854 (formerly known as Bellcore, which had been part of Bell Labs before the breakup of AT&T). At Telcordia, the Tactical Environment Assurance Laboratory (TEALab) created an environment for studying network attacks and attack recognition in ad hoc networking environments. The TEALab environment consists of a collection of mobile ad hoc network (MANET) hosts interconnected via a common networking environment such as an Ethernet (wired or wireless). Each MANET host can be viewed as consisting of four distinct “layers”: link layer communications, network-to-link layer filtering, network and transport layer communications, and applications. The link layer communications provides the physical and link layer protocols required to participate with the common networking environment. In a TEALab environment, this is an Ethernet protocol suite. The network-to-link layer filtering provides the functionality that controls whether one host will receive packets from another host. This is accomplished by the use of the netfilter/iptables system software. This software provides a set of hooks inside a Linux operating system that allow execution of software rules whenever network packets traverse the communications interface. The TEALab employs source filtering rules to restrict the in-flow of packets from hosts that are not considered to be next hop neighbors. As such, the environment can be viewed as one in which each host maintains a programmable switch between itself and the other hosts. The TEALab environment employs a Topology Scenario Management program to manipulate these filtering rules in real-time to emulate inter-nodal visibility. This program reads scenario scripts that define the network topology, changes it may undergo and when those changes occur. Thus both static and dynamic topologies can be defined. These topologies can be fully connected. For further details, see “TEALab: A Testbed for Ad hoc Networking Security Research.”
Studies of MANET have been conducted using mobility-pattern data, which can be generated by a computer program implementing a mobility model. However, frequently the data is purely time-stamped positions, lacking information about the links among the nodes, and thus insufficiently describe a static or dynamic topology.
Having a desirable dynamic topology meeting a specific need is important in the research, development, test, and evaluation of ad-hoc networks. During early phases of development, having a controllable specific topology is highly desirable because a new technique, algorithm, or mechanism that is being developed may not be ready to operate in any topology. During the last phases of the development, having a different topology is also desirable because it can be used to test and evaluate a newly developed technology in order to corroborate its performance claims. Accordingly, there exists a need for visually designing, editing, manipulating, verifying, and animating desired network topologies and creating desired mobility-pattern data of a mobile ad-hoc network (MANET). A desired network topology of a MANET system is a time-dependent geometrical shape and size of the network that meets at least the following requirements of a research need:
The exact number of participating nodes
Their relative geographical positions
The number of communication links of each node
Desired mobility-pattern data are time-stamped mobility traces that define a specific mobility scenario meeting a specific research need.